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Everything posted by gorann

  1. gorann

    Field flatness of refractor

    Thanks a lot Vlaiv! Then I have a go at it tomorrow if I manage to focus at 6 m. Supposed to be clear here tomorrow night so it would be nice to have it working.
  2. Whatever you do stay out of zoom lenses. Even those that costs more than 600 USD, like the Sigma APO 70-200 mm f/2.8 APO that I have give terrible stars in the corners, so it is only usable for daytime photography. Takumars are among the better cheap lenses that you can get used. I paied 100 USD for my Takumar 200 f/4 on ebay three years ago. Here are two links but I seem to remeber that I once also found an extensive review of the old cheap lenses but I cannot find it right now. https://www.cloudynights.com/articles/cat/articles/the-best-telephoto-lenses-for-astrophotography-r2993 http://www.astropix.com/html/i_astrop/lenses.html
  3. gorann

    Field flatness of refractor

    Yes, I also hoped @vlaiv would read this!
  4. gorann

    Field flatness of refractor

    I can probably get about 6 m between the scope and screen, so it could be worth a try but the question is if it would be the same distance between chip and flattener when I focus at 6 m as when imaging the sky. I assume David may find out tonight if the sky is clear. I have a sneaky feeling that the flattener is optimized for infinity focus (in my case it is an Esprit 100 flattener).
  5. gorann

    Field flatness of refractor

    Before I also try to find the correct distance to a flattener I am struggling with I would like to be sure that the flattener to chip distance is the same if I foucus on something close by (like a computer screen or sheet of paper) as if I focus on stars at night. Does anyone know?
  6. Good to know Olly. Now my only (rather significant) worry is that of having a mount dependent upon a computer rather than a simple handset......
  7. gorann

    M31 HaLRGB

    Rodd, on my job computer the sky color is better in the first one. It looks lilac/blue in the second one.
  8. gorann

    M31 HaLRGB

    Rodd, I have not had time to start a PS approach to your data yet but the week end is getting closer, and it is likely to be yet another cloudy one. Any chance you could post you non-DBE treated files? I do have plenty of other non-AP things I really should do so no pressure....
  9. I think I just fell into that trap by making the down payment for a Mesu mount, partly thanks to your continuous promotion of it Olly....
  10. That is exciting news! I assume Olly @ollypenrice will be one of the first to buy one if it comes past the beta version. I would have been one of the first if I had not recently bought an ASI1600MM since I gave up waiting for an APS-C sized mono CMOS camera. I wonder if they have manually removed the bayer mask or if they got Sony to produce a batch without them. In any case they will probably be a bit more costly than the color version.
  11. Sorry fro this double post. It was caused by the SGL site apparently being down for a while yesterday and when my job computer got connected again it sent it off again...... I do not agree that NB imaging, at least Ha, is very difficult/impossible with a OSC. Below is an image I took with my ASI071 (a APS-C sized cooled OSC) on an Esprit 150 and a Baader 7nm Ha filter. That being said, I have now also invested in an ASI1600mono for collecting NB side by side in another scope.
  12. Yes, that is an interestng filter Richard and it will be exciting to see what you can get out of it. I was about to order one when Wim pointed out to me that Oiii is often much weaker than Ha. So, in contrast to shooting with separate filters, with this combi filter you cannot compensate for that by exposure times since you may be overexposing Ha while underexposing Oiii. I imagine that it may work better on some objects than others depending on the Ha to Oiii signal ratio.
  13. You are most welcome Matt! If you go for a colour CMOS, you may think about going for an ASI071 rather than ASI294. A significantly bigger chip so more of the photons your scope collects will end up on you chip rather than around it, so more "real estate" as some here call it here. Will allow you in many cases to catch the whole object rather than a part of it.
  14. With my Esprit 150 and ASI071 (=0.94"/pixel) the focus is steadfast all night but then it is also at f/7 which is quite forgiving. Not sure yet how my Esprit 100 with f/5.5 will behave since I just got it before the clouds rolled in.
  15. Impressed! So when do you usualy go for breakfast?
  16. So you never go to sleep during your imagung nights Olly? Very impressed! I usuall go to bed after the meridean flip, turn on my rain alarm, and hope for the best.
  17. gorann

    M31 HaLRGB

    Rodd, I sincerely hope that you now have invested in an extra hard drive for backup! I have all my data (including all subs) duplicated on two external drives.
  18. Thanks! I have only used the ASI071 for NB with a Ha filter and it may be less satisfactory with the usually quite low intensity signals from Oiii and Sii, but much of the Oiii signal will be collected by the green channel (which means twize the number of pixels of the red channel) so Oiii may work.
  19. gorann

    M31 HaLRGB

    Very generous of you Rodd to post the data for us under the clouds! I have downloaded them and will have a go over the next days using PS.
  20. I do not fully agree that NB imaging, at least Ha, is very difficult/impossible with a OSC. Below is an image I took with my ASI071 (cooled OSC) on an Esprit 150 and a Baader 7nm Ha filter. Having said that, I have now also bought an ASI1600mono to collect NB with another scope side by side with the ASI071.
  21. gorann

    M31 HaLRGB

    Beautiful image Rodd! I am in the same situation as Wim and thanks to his comment I now know why my fingers are so itchy.....
  22. gorann

    Modded DSLR?

    I agree with Olly. If you can afford it (one day) go for a cooled CMOS camera (ZWO and QHY being the most popular brands) since they are significantly less noisy than un-cooled DSLRs. Also, I there are two variants of modding. The simplest is to remove the IR filter (to get more Ha) but you can also have the bayer mask removed to turn the DSLR into a mono camera to be used with filters (makes it more suitable for narrowband imaging). Finally, some people and companies even add cooling to the DSLR but then I really think one might as well go for a cooled CMOS camera.
  23. gorann

    ngc 869

    I rarely get thrilled by clusters but these are great images and almost thrilling! PS. Maybe you want to fix your misspelling in the subject line (so your image comes up in a search)
  24. gorann

    Seeing and The Elephants Trunk

    Seeing is a luxury problem. Here in Sweden there have been no stars to be seen for the last two weeks
  25. gorann

    Takahashi scopes???

    John, I did exactly that in April, upgraded from ES127 to Esprit 150, although I kept the ES127. Stars now look significantly better in my images. In fact, I found the Esprit to be such a nice scope that I recently also bought an Esprit 100 that is now sitting side by side with its big brother.

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